Gear shaft and method of manufacturing

ABSTRACT

A method of manufacturing a gear shaft including depositing only a first material via directed energy deposition (DED), forming a first portion of the gear shaft via the depositing only the first material via directed energy deposition (DED), forming a transitioning portion of the gear shaft via depositing of a varying ratio of the first material with a second material via DED, and forming a second portion of the gear shaft via the depositing via DED of only the second material.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 16/450,664 filed on Jun. 24, 2019, which is incorporated hereinby reference in its entirety.

BACKGROUND Technological Field

The present disclosure relates to gear shaft manufacturing, and moreparticularly to gear manufacturing using directed energy deposition.

Description of Related Art

Traditionally gear shafts are manufactured using welding to complete anassembled product. Gears of various materials are required to operate incertain environmental conditions. Welding operation is complex andcostly.

Thus, there is a need in the art to eliminate the need for welding ofgear shafts in order to reduce cost and lead time for manufacture ofgear assemblies while providing increase performance, life, andreliability of gear components. The present disclosure may provide asolution for at least one of these challenges.

SUMMARY OF THE INVENTION

A method of manufacturing a gear shaft includes depositing only a firstmaterial via directed energy deposition (DED), forming a first portionof the gear shaft via the depositing only the first material viadirected energy deposition (DED), forming a transitioning portion of thegear shaft via depositing of a varying ratio of the first material witha second material via DED, and forming a second portion of the gearshaft via the depositing via DED of only the second material. The shaftcan be manufactured by a continuous process and be machined a finaldimension of the first portion, the second portion, or the transitioningportion.

Forming the transitioning portion can include a single build directionfrom the first portion to the second portion. Forming the first portioncan include depositing the first material in powder or wire form.

A gear shaft includes a first portion including only a first material, asecond portion including only a second material, a transitioningportion, attached to both the first portion and the second portion,including a varying ratio of the first material to the second materialalong a length of the transitioning portion.

The transitioning portion can include a lengthwise majority of theshaft. The transitioning portion can include a gradient of the firstmaterial and a gradient of the second material there through. Thegradient can be constant, stepped, or exponential.

The first material can include a higher magnetic property than thesecond material. The first material can also include a highercoefficient of thermal expansion than the second material. The secondmaterial can include a second melting point and/or softening temperatureand/or a second shear strength that is less than a first melting pointand/or softening temperature and/or a first shear strength of the firstmaterial. The materials include titanium, aluminum, nickel or steel.

The amount of the first material can change at approximately 5% permillimeter over the length of the shaft portion and the amount of secondmaterial also changes at a rate of approximately 5% per millimeter overthe length of the shaft. The first amount of the first material isdifferent from the first amount of the second material.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,preferred embodiments thereof will be described in detail herein belowwith reference to certain figures, wherein:

FIG. 1 is a side view of a gear shaft showing an increasing amount of afirst material in a first along a length thereof and decreasing amountof a second material along the length thereof.

DETAILED DESCRIPTION

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a partial view of an exemplary embodiment of a gear shaft inaccordance with the disclosure is shown in FIG. 1 and is designatedgenerally by reference character 100. The methods and systems of thedisclosure can be used to simplify production of gear shafts, whileproviding safer manufacturing techniques and requiring less energy, andenabling gear assemblies that contain materials with mechanicalproperties very specific and tailored to the application.

FIG. 1 , shows a gear shaft 100 produced by directed energy deposition,the additive process in which metal wire or powder is deposited in alayer by layer manner to produce a near net shape final component. Afirst portion 102 of the gear shaft is formed by depositing on abaseplate a first amount of a first material by directed energydeposition (DED) using a powder or wire as a source of the materialwherein the first portion includes only the first material, forming atransitioning portion 104, attached to the first portion 102, bydepositing a varying amount of the first material by DED and a varyingamount of a second material by DED on an end 106 of the first portion102 wherein the transition portion 104 includes a mixtures of the firstand second materials and forming a second portion of the gear shaft,attached to the transitioning portion, by DED, wherein the secondportion 108 includes a second amount of the second material wherein thesecond portion 108 includes only the second material. The shaft 100 ismanufactured by a continuous process and the outer surface can later bemachined to a final dimension. Forming the transitioning portion 104includes a single build direction from the first portion 102 to thesecond portion 108.

Referring again to FIG. 1 , the gear shaft 100 includes a bevel gear 102configured to be used in a harsh operating environment, including afirst amount of a first material, the transition portion 104, attachedto the bevel gear 102, includes a decreasing amount of the firstmaterial along a length of the gear shaft and a second material whereinthe amount of the second material increases along the length of the gearshaft, and a second end, the second end 108 being a output gear shaftsection attached to the transitioning portion 104, wherein the secondportion includes a second amount of the second material. A gradientprovides properties for optimal performance in distinct systemenvironments, while entirely reducing the need for a complex joiningoperation.

As show in in FIG. 1 , the transitioning portion 104 includes alengthwise majority of the shaft 104. The transitioning portion 104includes a gradient of the first material and a gradient of the secondmaterial therethrough. The gradient can be constant, be stepped, or beexponential, depending on application requirements. The first materialincludes a different magnetic property than the second material and adifferent coefficient of thermal expansion than the second material. Thesecond material includes a second melting point and/or softeningtemperature and/or a second shear strength that is different than afirst melting point and/or softening temperature and/or a first shearstrength of the first material. The materials include titanium,aluminum, nickel or steel. The amount of the first material can changeat approximately 5% per millimeter over the length of the shaft 100 andthe amount of second material also changes at a rate of approximately 5%per millimeter over the length of the shaft 100 as well. This transitionrate ensures this shaft will be able to withstand both structural andthermal loads.

Traditional methods have produced gear shafts including a definitiveborder between a first material and the second material, which result ina shorter time between failures and increased risk of defects related tojoining methods.

The methods and systems of the present disclosure, as described aboveand shown in the drawings, provide for gear shaft with superiorproperties including increased reliability and stability, and/cost.While the apparatus and methods of the subject disclosure have beenshown and described with reference to embodiments, those skilled in theart will readily appreciate that changes and/or modifications may bemade thereto without departing from the spirit and score of the subjectdisclosure.

What is claimed is:
 1. A gear shaft comprising: a first portionincluding only a first material; a second portion including only asecond material; and a transitioning portion, attached to both the firstportion and the second portion, including a varying ratio of the firstmaterial to the second material along a length of the transitioningportion, wherein the transitioning portion includes a lengthwisemajority of the shaft.
 2. The shaft of claim 1, wherein thetransitioning portion includes a gradient of the first material and agradient of the second material there through.
 3. The shaft of claim 2,wherein the gradient of the first material is 5% per millimeter.
 4. Theshaft of claim 2, wherein the gradient of the second material is 5% permillimeter.
 5. The shaft of claim 2, wherein the gradient is constant,stepped, or exponential.
 6. The shaft of claim 1, wherein the firstmaterial includes a higher magnetic property than the second material ina given magnetic field.
 7. The shaft of claim 1, wherein the firstmaterial includes a higher coefficient of thermal expansion than thesecond material at a given temperature.
 8. The shaft of claim 1, whereinthe second material includes a second melting point and/or softeningtemperature and/or a second shear strength that is less than a firstmelting point and/or softening temperature and/or a first shear strengthof the first material.
 9. The shaft of claim 1, wherein the materialsinclude titanium, aluminum, nickel or steel.